The cadherin superfamily of adhesion molecules encompasses over 100 members, which can be subdivided into classical cadherins, desmosomal cadherins, and protocadherins. Many classical cadherins and protocadherins are expressed in the central nervous system (CNS), where they have been implicated in a wide variety of processes. The ∼20 classical cadherins have 5 characteristic cadherin repeats and an intracellular domain that contains binding sites for members of the catenin family. The classical cadherins are important for a number of processes integral to the synapse, including axon targeting, dendrite and dendritic spine maturation, and synapse function and plasticity. The more than 70 protocadherins (Pcdhs) make up the largest subgroup of the cadherin superfamily, which includes the clustered α-, β-, and γ-Pcdhs, the δ-Pcdhs, the seven-transmembrane (7-TM) Pcdhs, and the giant fat Pcdhs. These diverse molecules, all of which contain a varying number of cadherin repeats, play a multitude of roles in synapse development and function. Of the clustered Pcdhs, the γ-Pcdhs are required for synapse development and interneuron survival in the spinal cord, while the α-Pcdhs influence axon targeting, as do the 7-TM Pcdhs. Several of the δ-Pcdhs and fat Pcdhs have demonstrated and/or suggested functions at the synapse. This chapter reviews the vast extant literature on the cadherin superfamily, summarizing key findings regarding its diverse members and their functions at central synapses. Particular attention is paid to the most recent results, including the fascinating demonstration of cooperation between synaptic classical cadherins and Pcdhs.